Bi-Amp reQuest with class D amplifiers (Crown)?

[Dobbler]

<moved from another thread for visibility>

I've done a dozen searches and not come up with an answer on this one.

Is it possible to bi-amp a set of reQuests with a pair of Crown XLS Class D amplifiers? Either horizontal or vertical. I am confident I can drive the low end woofers, but what about the panels? Will I start a fire? LOL I'm thinking about two of XLS1002 (350w @ 4Ω, 550w @ 2Ω).

 

[Russr]

I seem to be doing this a lot these days, sorry Brandon, but I believe @Brandon Hartwick will have some insights. I'm keen of pursuing a similar path, myself, but I want my existing Bryston amps to drive my SL3 panels, and use the Crowns with the woofers...

 

[Dobbler]

I seem to be doing this a lot these days, sorry Brandon, but I believe @Brandon Hartwick will have some insights. I'm keen of pursuing a similar path, myself, but I want my existing Bryston amps to drive my SL3 panels, and use the Crowns with the woofers...

I’d like to retire my large, hot and aging Classe multi channel amp. It runs fine but if I can get the similar sound quality for less $, less power draw and less heat…

 

[JonFo]

Is it possible to bi-amp a set of reQuests with a pair of Crown XLS Class D amplifiers?

Short answer: no. The Crowns are perfect for the woofers, but they won't like the ESL. Continue using the Classe for the panels and add a Crown to bi-amp the woofers. Remember to remove the input binding straps on the speaker.

Even better yet, do an active woofer section as we've been discussing recently here on threads like these:

Passive Crossover bypass – Quest / reQuest

Some members have been asking for help in figuring out how to bypass the factory crossover in the Quest / reQuests so they can use active crossovers. So here is a short description and attached is a schematic for how to bypass the passive crossover. This applies to most models of first-gen ESL...

www.martinloganowners.com

XO Info: ReQuest Crossover schematic

If you use a Crown with built-in DSP, then you only need one box for the woofer amplification and low-pass XO.

 

[Dobbler]

Thank you @JonFo

I've been running the reQuests passively bi-amped with the Classe CAV-150 since I bought the speakers new in 1996 (~ 300w @ 4Ω x 4).

The active woofer mod was what caught my attention initially, and then I started down this rabbit hole...

I'd still like to replace the 70lb Classe space heater, so I'll look for 2 channel alternatives for the panels to mate with the XLS-1002 on the woofers.

I proactively replaced my panels (in 2011?) and was told by ML that I have the last set of original reQuest panels made. Since then, of course, ML has started making the newer panels for older models. I wonder if that's a worthwhile endeavour or just an expensive side grade?

 

[Asepguy]

Short answer: no. The Crowns are perfect for the woofers, but they won't like the ESL. Continue

what’s the reasoning for this?

 

[JonFo]

what’s the reasoning for this?

The power supplies in most Pro-level class-D amps are not designed to deliver the voltages needed by the panels, and the super-low impedance and back-EMF from what is essentially a giant capacitor (as far as the amp is concerned) is not something they handle. They are designed for resistive loads (voice-coil dynamic speakers) and can go into oscillation (sounds horrible) and / or thermal shutdown (or fry if poorly designed).
They will run for a while or at low levels, but push them, and bad things happen.

There is a reason a Sanders Sound Systems ESL amp weighs 5x as much and can deliver colossal voltage and amperage output (2000 volt-amps/channel) from the 20 large output transistors per channel fed by a large toroidal transformer and plenty of reserves in the capacitor banks.

 

[JonFo]

I'd still like to replace the 70lb Classe space heater, so I'll look for 2 channel alternatives for the panels to mate with the XLS-1002 on the woofers.

As noted in the previous post, I recommend the Sanders ESL amp without reservations. It barely gets warm after driving my Monolith panels (direct) for hours.

 

[Dobbler]

As noted in the previous post, I recommend the Sanders ESL amp without reservations. It barely gets warm after driving my Monolith panels (direct) for hours.

Yeah, that's going the other direction $$$ LOL.

 

[Brandon Hartwick]

As others have stated, I personally wouldn't go with a class D pro audio amp on the panels, maybe if it's rated down to 2 ohm. Mini DSP and Dayton both make external crossover/DSP units if you wanted to go that route instead.

I personally wouldn't replace the panels unless there's something wrong with them, those things are getting crazy expensive to replace.

 

[Russr]

Here's the thread where Brandon describes how he did pretty much what you're looking for, but on Aerius speakers... I don't see any reason this would not work in your case, but, as others have said,, if you have an amp that handles the full range today (even if they ARE room heaters), continue using them to drive the panels. You will probably still realize a net-reduction in heat generated and power consumption by sending the LFs to the class D Crown amp...

How to: active bass section

I recently defeated the internal woofer crossover in my Aerius i's and drove it with its own amplifier with an active electronic crossover. This modification totally brought these speakers to a whole new level. This is how the bass is handled in the newer Martin Logan models. Below I will...

www.martinloganowners.com

 

[Brandon Hartwick]

I’d like to retire my large, hot and aging Classe multi channel amp. It runs fine but if I can get the similar sound quality for less $, less power draw and less heat…

Few options do so what you want

I didn't realize the Classe amp you have is 6 channels. You could easily just add a processor between your amp and pre amp and whatever you want with the passive crossovers. You could go active on everything, or just the bass, you'd still have enough outputs to handle an additional subwoofer.

Dayton Audio - DSP-408 4x8 DSP Digital Signal Processor for Home and Car Audio

DSP-408 4x8 DSP Digital Signal Processor for Home and Car Audio

www.daytonaudio.com

Alternatively you could replace that massive Classe amplifier with something more economical and then just use an amp with built in active crossovers/DSP for the woofers.